AER Lingus begins operating its first ever domestic British flights tomorrow – but it's doing it under contract for Richard Branson's Virgin Atlantic.

The two airlines had been in competition last year to secure prized take-off and landing slots at London's Heathrow Airport that were relinquished by British Airways as part of its deal with regulators to be able to buy British Midland.

Aer Lingus and Virgin were pitched against each other last year in a bid to gain control of slots to operate a service between Heathrow and Edinburgh.

But Virgin won the slots, leaving Aer Lingus disappointed. Headed by Christoph Mueller, Aer Lingus has been eyeing ways to expand its business outside Ireland, where it generates the bulk of its revenue but where the aviation market remains depressed.

Weeks later, the two airlines announced that they had agreed a three-year deal where Aer Lingus will operate flights on behalf of Virgin Atlantic, which is 49pc-owned by US airline Delta.

That's being done using what's called a 'wet lease' agreement, where Aer Lingus provides the aircraft and crew.

The four Airbus aircraft will be painted in Virgin Atlantic livery and the crew will be dressed in Virgin Atlantic uniforms. The aircraft will be used to service Virgin Atlantic flights from London to Manchester, Edinburgh and Aberdeen.

The first flight under the deal is due to take off tomorrow morning, flying between Manchester and Heathrow. The new services, including those to Scotland, will include 24 daily flights.

Mr Mueller has said that he'd be interested in securing additional wet lease agreements with other operators in a bid to widen the Aer Lingus revenue base.